This invention is concerned with a new member of the glycopeptide group of antibiotics, a class of compounds characterised biologically by their Gram-positive antibacterial action exerted by the inhibition of bacterial cell wall biosynthesis. This family of antibiotics includes such well known agents as avoparcin; actaplanin; teichoplanin; A41030 complex and the aridicins. The subject has been reviewed by Williams and Barna. "Structure and mode of action of glycopeptide antibiotics of the vancomycin group". Annual Rev. Microbiol., 38, 339, 1984.
In the search for new antibiotics, structural modification of known antibiotics is attempted whenever possible. This approach is limited, however, to modifications which retain the desired activity. Many antibiotics, including the glycopeptides, have such complex structures that even small changes can be difficult to make by chemical means. The discovery of new antibiotics produced by fermentation processes continues, therefore, to be of great importance even in cases where the antibiotic, once recognized, is quite similar to a previously known antibiotic.
The glycopeptide antibiotics listed above are active against Gram-positive bacteria. They have therefore been employed with varying degrees of success for administration to poultry and other farm animals, including the ruminants and pigs, to control infection or to promote growth or milk production.
Among a number of conditions which can be treated with these agents is enteritis, a disease which can cause severe economic losses to livestock producers. Enteritis occurs in chickens, swine, cattle and sheep and is attributed mainly to anaerobic bacteria, particularly Clostridium perfringens, and viruses. Enterotoxemia in ruminants, an example of which is "overeating disease" in sheep, is a condition caused by C. perfringens infection.
Performance enhancement (increased rate of growth and/or increased efficiency of feed utilization) in ruminants such as cattle, and in monogastric animals such as swine, is another economically desirable objective of veterinary science. Of particular interest is improved performance achieved by increasing the efficiency of feed-utilization. The mechanism for utilization of the major nutritive portion of ruminant feeds is well known. Microorganisms in the rumen of the animal degrade carbohydrates to produce monosaccharides and then convert these monosaccharides to pyruvate compounds. Pyruvates are metabolized by microbiological processes to form acetates, butyrates or propionates, collectively known as volatile fatty acids. Although acetates and butyrates are utilized, propionates are utilized with greater efficiency. Furthermore, when too little propionate is available, animals may develop ketosis. A beneficial compound, therefore, stimulates animals to produce a higher proportion of propionates from carbohydrates, thereby increasing carbohydrate utilization efficiency and also reducing the incidence of ketosis.